Bank subsidiary (Details 9) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Credit risk profile based on payment activity for loans
30-59 days past due	$ 5,814	$ 14,016
60-89 days past due	2,430	5,120
Greater than 90 days	29,369	41,433
Total past due	37,613	60,569
Current	4,017,776	3,730,287
Total financing receivables	4,055,389	3,790,856	3,757,903
Recorded Investment greater than 90 days and accruing	1,746	373
Residential 1-4 family
Credit risk profile based on payment activity for loans
30-59 days past due	3,026	6,353
60-89 days past due	1,599	1,741
Greater than 90 days	15,060	24,054
Total past due	19,685	32,148
Current	1,995,397	1,834,302
Total financing receivables	2,015,082	1,866,450	1,899,580
Commercial real estate
Credit risk profile based on payment activity for loans
30-59 days past due		85
Greater than 90 days	3,790	6,750
Total past due	3,790	6,835
Current	401,247	368,842
Total financing receivables	405,037	375,677	367,765
Home equity line of credit
Credit risk profile based on payment activity for loans
30-59 days past due	658	1,077
60-89 days past due	373	142
Greater than 90 days	880	1,319
Total past due	1,911	2,538
Current	701,299	627,637
Total financing receivables	703,210	630,175	604,279
Residential land
Credit risk profile based on payment activity for loans
30-59 days past due	684	2,851
60-89 days past due	80	75
Greater than 90 days	5,352	7,788
Total past due	6,116	10,714
Current	12,284	15,101
Total financing receivables	18,400	25,815	29,280
Recorded Investment greater than 90 days and accruing	1,746
Commercial construction
Credit risk profile based on payment activity for loans
Current	51,067	43,988
Total financing receivables	51,067	43,988	42,913
Residential construction
Credit risk profile based on payment activity for loans
Current	10,460	6,171
Total financing receivables	10,460	6,171	5,648
Commercial loans
Credit risk profile based on payment activity for loans
30-59 days past due	1,026	3,052
60-89 days past due	166	2,814
Greater than 90 days	4,105	1,098
Total past due	5,297	6,964
Current	744,436	714,385
Total financing receivables	749,733	721,349	704,100
Recorded Investment greater than 90 days and accruing		131
Consumer loans
Credit risk profile based on payment activity for loans
30-59 days past due	420	598
60-89 days past due	212	348
Greater than 90 days	182	424
Total past due	814	1,370
Current	101,586	119,861
Total financing receivables	102,400	121,231	104,338
Recorded Investment greater than 90 days and accruing		$ 242